Se conocen varios ‘alótropos del oxígeno. entre los cuales el más familiar es el oxígeno molecular (O2), abundantemente presente en la atmósfera terrestre y. Los alótropos del carbono son los siguientes: diamante es uno de los alótropos del carbono mejor conocidos, cuya dureza y alta dispersión. Reconocer las características del átomo de carbono y su capacidad para formar Video de Propiedades; Ubicación en Tabla Periódica; Alótropos; Estructura.

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Carbon is capable of forming many allotropes due to its valency. Well-known forms of carbon include diamond and graphite. In recent decades many more allotropes are forms of carbon have been discovered and researched including ball shapes such as buckminsterfullerene and sheets such as graphene.

Larger scale structures of carbon include nanotubesnanobuds and nanoribbons. Other unusual forms of carbon exist at very high temperatures or extreme pressures. Around hypothetical 3-periodic allotropes of carbon are known at the present time according to SACADA [1] database. Diamond is a well known allotrope of carbon.

Diamond is the hardest known natural mineral. This makes it an excellent abrasive and makes it hold polish and luster extremely well. No known naturally occurring substance can cut or even scratch a diamond, except another diamond. The market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the gemological characteristics of diamond, including clarity and color, mostly irrelevant.

In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the s; another million carats 80 tonnes of synthetic diamonds are produced annually for industrial use, which is nearly four times the mass of natural diamonds mined over the same period.

The dominant industrial use of diamond is in cuttingdrilling drill bitsgrinding diamond edged cuttersand polishing. Most uses of diamonds in these technologies do not require large diamonds; in fact, most diamonds that are not gem-quality can find an industrial use.

Propiedades del carbono | Portal Académico del CCH

Diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications due to alotdopos extraordinary hardness.

Specialized applications include use in laboratories as containment for high pressure experiments see diamond anvilhigh-performance bearingsand limited use in specialized windows.

With the continuing advances being made in the production of synthetic diamond, future applications are beginning to become feasible. Garnering much excitement is the possible use of diamond as a semiconductor suitable to build microchips from, or the use of diamond as a heat sink in alotropow. Significant research efforts in JapanEuropeand the United States are under way to capitalize on the potential offered by diamond’s unique material properties, combined with increased quality and quantity of supply starting to become available from synthetic diamond manufacturers.

Each carbon atom in a diamond is covalently bonded to carbojo other carbons in a tetrahedron. Carnono tetrahedrons together form a 3-dimensional network of six-membered carbon rings similar to cyclohexanein the chair conformationallowing for zero bond angle strain.

This stable network of covalent bonds and hexagonal rings is the reason that diamond is so strong. Unlike diamond, graphite is an electrical conductor. Thus, it can be used in, for instance, electrical arc lamp electrodes. Likewise, under standard conditionsgraphite is the most stable form of carbon.

Therefore, it is used in thermochemistry as the standard state for defining the heat of cagbono of carbon compounds. Graphite conducts electricitydue to delocalization of the pi bond electrons above and below the planes of the carbon atoms. These electrons are free to move, so are able to conduct electricity.


However, the electricity is only conducted along the plane of the layers. In diamond, all four outer electrons of each carbon atom are ‘localised’ between the atoms in covalent carvono. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes alltropos electron to a delocalised system of electrons that is also a part of the chemical bonding.

The delocalised electrons are free to move throughout the plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct in a direction at right angles to the plane. Graphite powder is used as a dry lubricant.

Although it might be thought that this industrially important property is due entirely to the loose interlamellar coupling between sheets in the structure, in fact in a vacuum environment such as in technologies for use in spacegraphite was found to be a very poor lubricant.

This fact led to the discovery that graphite’s lubricity is due to adsorbed air and water between the layers, unlike other layered dry lubricants such as molybdenum disulfide.

Recent studies suggest that an effect called superlubricity can also account for this effect. When a large number of crystallographic defects bind these planes together, graphite loses its lubrication properties and becomes what is known as pyrolytic carbona useful material in blood-contacting implants such as prosthetic heart valves.

Graphite is the most stable allotrope of carbon. Contrary to popular belief, high-purity graphite does not readily burn, even at elevated temperatures.

Natural and crystalline graphites are not often used in pure form as structural materials due to their shear-planes, brittleness and inconsistent mechanical properties. Intumescent or expandable graphites are used in fire seals, fitted around the perimeter of a fire door. During a fire the graphite intumesces expands and chars to resist fire penetration and prevent the spread of fumes.

This is because the reactants are able to penetrate between the hexagonal layers of carbon atoms in graphite. It is unaffected by ordinary solvents, dilute acids, or fused alkalis. However, chromic acid oxidises it to carbon dioxide.

A single layer of graphite is called graphene and has extraordinary electrical, thermal, and physical properties. It can be produced by epitaxy on an insulating or conducting substrate or by mechanical exfoliation repeated peeling from graphite. Its applications may include replacing silicon in high-performance electronic devices. With two layers stacked, bilayer graphene results with different properties. Graphenylene [5] is a single layer carbon material with biphenylene -like subunits as basis in its hexagonal lattice structure.

It is also known as biphenylene-carbon. AA’-graphite is an allotrope of carbon similar to graphite, but where the layers are positioned differently to each other as compared to the order in graphite. Amorphous carbon is the name used for carbon that does not have any crystalline structure. As with all glassy materials, some short-range order can be observed, but there is no long-range pattern of atomic positions. While entirely amorphous carbon can be produced, most amorphous carbon actually contains microscopic crystals of graphite -like, [6] or even diamond -like carbon.

Coal and soot or carbon black are informally called amorphous carbon. However, they are products of pyrolysis the process of decomposing a substance by the action of heatwhich does not produce true amorphous carbon under normal conditions. The buckminsterfullerenesor usually just fullerenes or buckyballs for short, were discovered in by a team of scientists from Rice University and the University of Sussex, three of whom were awarded the Nobel Prize in Chemistry.

They are named for the resemblance to the geodesic structures devised by Richard Buckminster “Bucky” Fuller. Fullerenes are positively curved molecules of varying sizes composed entirely of carbon, which take the form of a hollow sphere, ellipsoid, or tube.


Alótropos del oxígeno

As of the early twenty-first century, the chemical and physical properties of fullerenes are still under heavy study, in both pure and applied research labs.

Carbon nanotubes, also called buckytubes, are cylindrical carbon molecules with novel properties that make them potentially useful in a wide variety of applications e. They exhibit extraordinary strength, unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized. A nanotube is a member of the fullerene structural family, which also includes buckyballs.

Whereas buckyballs are spherical in shape, a nanotube is cylindricalwith at least one end typically capped with a hemisphere of the alotropod structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers approximately 50, times smaller than the width of a human hairwhile they can be up to several centimeters in length. There are two main types of nanotubes: Carbon nanobuds are a newly discovered allotrope of carbon in which fullerene like “buds” are covalently attached to the outer sidewalls of the carbon nanotubes.

This alotropoos material has useful properties alootropos both fullerenes and carbon nanotubes. For instance, crbono have been found alotropo be exceptionally good field emitters.

Schwarzites are negatively curved carbon molecules. A negatively curved object bends inwards like a saddle rather than bending outwards like a sphere. The team that first created schwarzites did not recognize them as such. Instead they were called zeolite-templated carbons ZTCs. The name derives from their origin inside the pores of zeolitescrystalline silicon dioxide minerals.

Another team recognized them as schwarzites and refined the original synthesis technique. A vapor of carbon-containing molecules is injected into the zeolite, where the carbon gathers on the pores’ inner walls. It forms a 2D sheet caarbono pulls inwards, creating the negative curve.

Dissolving the zeolite leaves the carbon. Glassy carbon or vitreous carbon is a class of non-graphitizing carbon widely used as an electrode material in electrochemistryas well as for high-temperature crucibles and as a component of some prosthetic devices.

He had set out to develop a polymer matrix to mirror a diamond structure and discovered a resole phenolic resin that would, with special preparation, set without a catalyst. Using this resin the first glassy carbon was produced. Unlike many non-graphitizing carbons, they are impermeable to gases and are chemically extremely inert, especially those prepared at very high temperatures.

It has been demonstrated that the rates of oxidation of certain glassy carbons in oxygen, carbon dioxide or water vapour are lower than those of any other carbon. They are also highly resistant to attack by acids. Thus, while normal graphite is reduced to a powder by a mixture of concentrated sulfuric and nitric acids at room temperature, glassy carbon is unaffected by such treatment, even after several months. Under certain conditions, carbon can be found in its atomic form.

It is formed by passing large electric currents through carbon under very low pressures. It is extremely unstable, but it is an intermittent product used in the creation of carbenes.

Allotropes of carbon

Diatomic carbon can also be found under certain conditions. It is often detected via spectroscopy in extraterrestrial bodies, including comets and certain stars. Carbon nanofoam is the fifth known allotrope of carbon, discovered in by Andrei V. Rode and co-workers at the Australian National University in Canberra.

It consists of a low-density cluster-assembly of carbon atoms strung together in a loose three-dimensional web.